CN110462191B

CN110462191B - Control device for vehicle engine

Info

Publication number: CN110462191B
Application number: CN201880022023.9A
Authority: CN
Inventors: 马场悠一; 川越纯
Original assignee: Mikuni Corp
Current assignee: Mikuni Corp
Priority date: 2017-03-31
Filing date: 2018-01-25
Publication date: 2022-02-18
Anticipated expiration: 2038-01-25
Also published as: WO2018179762A1; JP2018173002A; CN110462191A; JP6794307B2

Abstract

A control device for a vehicle engine includes: an intake passage (11); a throttle valve (13); a bypass passage (15) that bypasses the throttle valve (13); an idle speed control valve (14) provided in the bypass passage (15); a revolution sensor (32); a throttle sensor (33); a fuel cut element (31); a control element (31), wherein the control element (31) maintains the engine speed at idle at a preset target speed by controlling the opening degree of the idle speed control valve (14); and an abnormality determination element (31) that determines that an idling abnormality has occurred when the engine (1) is idling, the throttle opening is equal to or less than a predetermined first opening threshold, and the number of fuel cuts is equal to or greater than a predetermined number threshold within a predetermined time.

Description

Control device for vehicle engine

Technical Field

The present invention relates to a control device for an engine for a vehicle, and more particularly to a control device for detecting and responding to an idling abnormality of an engine mounted on a motorcycle.

Background

Patent document 1 discloses a control device for a vehicle engine, including: an intake passage connected to the engine; a throttle valve provided in the intake passage; a bypass passage connected to the intake passage and bypassing the throttle valve; and an idle speed control valve (hereinafter also referred to as an ISCV) provided in the bypass passage. Even if the throttle opening of the throttle valve is maintained in a fully closed or slightly opened state during idling of the engine, the opening of the ISCV is controlled to adjust the amount of intake air to the engine, thereby maintaining the engine speed at a predetermined value.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2011-80480

Disclosure of Invention

Technical problem to be solved by the invention

However, when the dirt adhering to the ISCV becomes hard and the ISCV is fixed in a state of opening the valve, that is, when so-called opening fixation occurs, there is a possibility that the ISCV cannot be controlled at the time of engine idling. If the ISCV cannot be controlled and the intake air amount to the engine is increased, the engine speed increases to an unexpected speed, and the idle speed control of the engine cannot be appropriately performed.

Further, as described in patent document 1, when the target opening degree of the ISCV is determined based on learning, the opening degree of the ISCV may not be appropriately controlled due to erroneous learning or the like caused by the operating condition of the vehicle, and an idling abnormality of the engine may occur. Therefore, conventionally, it is necessary to detect an idling abnormality of the engine.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a control device for a vehicle engine, which can detect an idling abnormality of the engine.

Means for solving the problems

In order to achieve the above object, a control device for a vehicle engine according to the present invention includes: an intake passage connected to the engine; a throttle valve provided in the intake passage; a bypass passage that is connected to the intake passage and that bypasses the throttle valve; an idle speed control valve provided in the bypass passage; a revolution sensor that detects the number of engine revolutions; a throttle sensor that detects a throttle opening of the throttle valve; a fuel cut-off element that cuts off fuel supply to the engine when the engine speed is greater than a prescribed upper limit speed and the opening degree is less than a prescribed lower limit opening degree while the engine is idling; a control element that controls an opening degree of the idle speed control valve based on the engine revolution detected by the revolution sensor and the throttle opening degree detected by the throttle sensor so as to maintain the engine revolution at a preset target revolution when the engine is idling; and an abnormality determination element that determines that an idling abnormality has occurred when the throttle opening is equal to or less than a predetermined first opening threshold and the number of times of fuel cut by the fuel cut element is equal to or more than a predetermined number threshold within a predetermined time while the engine is idling.

On the other hand, another vehicle engine control device according to the present invention includes: an intake passage connected to the engine; a throttle valve provided in the intake passage; a bypass passage that is connected to the intake passage and that bypasses the throttle valve; an idle speed control valve provided in the bypass passage; a revolution sensor that detects the number of engine revolutions; a throttle sensor that detects a throttle opening of the throttle valve; a control element that adjusts an opening degree of the idle speed control valve based on the engine revolution detected by the revolution sensor and the throttle opening degree detected by the throttle sensor so as to maintain the engine revolution at a preset target revolution when the engine is idling; and an abnormality determination element that determines that an idling abnormality has occurred when the engine speed is greater than a predetermined first speed threshold value, the engine speed is greater than or equal to a value obtained by adding a target speed to a predetermined second speed threshold value, the engine speed continues to be less than a predetermined third speed threshold value for a predetermined time after the control device is started, and the state continues for a predetermined time, when the state continues.

Preferably, the control device for the vehicle engine further includes an abnormality determining unit configured to determine that the idle speed control valve is in a fixed open state in an open state as the idle abnormality when the engine speed is greater than a value obtained by adding the target speed and a predetermined fourth speed threshold and the drive duty ratio is zero for a predetermined time after the abnormality determining unit determines that the idle speed abnormality has occurred.

Preferably, the control device for the vehicle engine further includes an abnormality determining element that determines that the idling control valve is in an open-fixed state in which the idling control valve is in an open-fixed state when the abnormality determining element determines that the idling control valve is in the open-fixed state after determining that the idling abnormality has occurred by the abnormality determining element, and the fuel cut element cuts off the supply of fuel to the engine when determining that the idling control valve is in the open-fixed state by the abnormality determining element, the control element sets the drive duty of the idling control valve to zero.

Preferably, the control device determines a correction value by learning, the correction value correcting an opening degree of the idle speed control valve when the engine is idling, and the abnormality determining device determines that the error learning of the correction value learned by the control device has occurred as the idle abnormality when a state in which the engine speed is equal to or less than a value obtained by adding the target speed and a predetermined fifth speed threshold continues for a predetermined time.

Preferably, the control device for an engine of a vehicle further includes an abnormality determining device that determines that the error learning of the correction value learned by the control device has occurred as the idling abnormality when a state in which the number of engine revolutions is equal to or less than a value obtained by adding the target number of revolutions to a predetermined fifth threshold number of revolutions continues for a predetermined time after the abnormality determining device determines that the idling abnormality has occurred, and the control device sets the drive duty of the idling control valve to zero.

Preferably, the control element changes the correction value such that the drive duty of the idle speed control valve is decreased when it is determined by the abnormality determining element that the erroneous learning of the correction value has occurred.

Effects of the invention

According to the control device for the vehicle engine of the present invention, the idling abnormality of the engine can be detected.

Drawings

Fig. 1 is a system configuration diagram showing a control device for a vehicle engine according to an embodiment of the present invention.

Fig. 2 is a flowchart showing tentative determination a executed by the ECU of fig. 1.

Fig. 3 is a flowchart showing tentative determination B executed by the ECU of fig. 1.

Fig. 4 is a flowchart showing a determination judgment X executed by the ECU of fig. 1.

Fig. 5 is a flowchart showing a determination judgment Y executed by the ECU of fig. 1.

Detailed Description

Hereinafter, a control device for a vehicle engine according to an embodiment of the present invention will be described with reference to the drawings.

Fig. 1 is a configuration diagram showing a control device of the engine 1. The vehicle is, for example, a motorcycle, and the engine 1 is, for example, a four-stroke single-cylinder gasoline engine having an exhaust gas volume of 50cc, and is a power source for running of the motorcycle. The specification of the engine 1 is not limited to fig. 1 and can be changed arbitrarily. In addition, the illustration and description of the apparent components of the motorcycle are omitted as appropriate.

A flywheel 7 is attached to a rear end (a transmission side not shown) of a crankshaft 6 that rotates by operation of the engine 1. A variable reluctance rotor 7a for detecting a crank angle is formed at a predetermined position on the outer periphery of the flywheel 7.

The engine 1 is formed with an intake port 9a and an exhaust port 9 b. An intake passage 11 is connected to the intake port 9 a. In the intake passage 11, a throttle valve 13 and an injector 16 are provided in this order from the upstream side in the flow direction of the intake air.

The throttle valve 13 is opened and closed according to the throttle operation by the driver. Further, the injector 16 injects fuel toward the intake port 9 a. A bypass passage 15 that bypasses the throttle valve 13 is connected to the intake passage 11, and an ISCV (idle speed control valve) 14 is provided in the bypass passage 15. On the other hand, an exhaust passage 17 is connected to the exhaust port 9 b.

The ISCV14 is a so-called Duty SoleNoid Valve (Duty SoleNoid Valve) that adjusts the opening degree by driving a Duty (a ratio of on time to the total of on time and off time). Here, the on-time is a time to open the ISCV14, and the off-time is a time to close the ISCV 14. Even if the throttle opening θ th of the throttle valve 13 is maintained in the fully closed or slightly opened state when the engine 1 is idling, the ISCV14 can maintain the engine speed Ne at the preset target speed Net by adjusting the intake air amount to the engine 1 by the opening degree control of the ISCV 14.

The opening degree of the ISCV14 is adjusted by feedback-controlling the drive duty ratio of the ISCV14 so that the engine speed Ne at the time of idling becomes the target speed Net. The feedback control uses a correction value that takes into account the effects of device variations, changes over time, and the like of the engine 1, the running environment of the vehicle, and the like. The correction value is a value for correcting the drive duty ratio of the ISCV 14. The correction value is updated as needed by learning so that the opening degree of the ISCV14 coincides with the target opening degree.

More specifically, when the engine speed Ne at the time of idling is higher than the first threshold value th1, the above correction value is updated so that the drive duty ratio of the ISCV14 is smaller. On the other hand, when the engine speed Ne at the time of idling is lower than the second threshold value th2, the correction value is updated so that the drive duty ratio of the ISCV14 becomes larger. Here, the first threshold value th1 and the second threshold value th2 are set in advance such that "the first threshold value th1 > the target rotation number Net > the second threshold value th 2" holds.

Fuel such as gasoline stored in a fuel tank 25 is supplied to the injector 16 by a fuel pump 26. The fuel pump 26 can pressurize and supply fuel. The fuel pump 26 and the injector 16 are integrally configured, and are connected to the fuel tank 25 via a supply hose 27 and a return hose 28, respectively.

When the fuel pump 26 is operated, the fuel in the fuel tank 25 is introduced into the fuel pump 26 through the supply hose 27 and pressurized to a predetermined pressure, and the pressurized fuel is supplied to the injector 16. Since the surplus fuel in the injector 16 is recovered to the fuel tank 25 via the return hose 28, the fuel of a predetermined pressure is always supplied to the injector 16. Thereby, the fuel of a predetermined injection timing and injection amount is injected toward the intake port 9a by opening the injector 16.

During operation of the engine 1, during an intake stroke, outside air is drawn into the intake passage 11. The intake air drawn into the intake passage 11 is subjected to flow rate adjustment in accordance with the throttle opening θ th of the throttle valve 13, mixed with the fuel injected from the injector 16, and introduced into the cylinder of the engine 1. The compressed air-fuel mixture in the next compression stroke is ignited and burned in the expansion stroke, thereby applying a rotational force to the crankshaft 6. In the next exhaust stroke, the burned exhaust gas is discharged from the cylinder of the engine 1 to the outside via the exhaust passage 17.

The combustion cycle of the engine 1 described above is executed based on control by the ECU31 (engine control unit). The ECU31 has a processor (not shown), and functions as a control element, a fuel cut element, an abnormality determination element, and an abnormality specification element by executing programs that implement various steps described later on with the processor. Various sensors such as an electromagnetic pickup (rotation number sensor) 32 and a throttle sensor 33 are connected to an input side of the ECU31, and switches such as a neutral SW (neutral switch) 37 and a clutch SW (clutch switch) 38 are also connected thereto.

The electromagnetic pickup 32 is disposed to face the flywheel 7, and outputs a crank angle signal synchronized with the approach of the variable reluctance rotor 7a accompanying the rotation of the flywheel 7. The throttle sensor 33 detects a throttle opening θ th of the throttle valve 13.

When the gear position of the transmission, not shown, of the vehicle is in the neutral position, neutral SW37 is turned on. When the clutch, not shown, is disengaged from the engine 1 or the transmission, the clutch SW38 is engaged. Various devices such as the throttle valve 13, the ISCV14, the injector 16, and the fuel pump 26 are connected to the output side of the ECU 31.

The ECU31 executes various controls to operate the engine 1: fuel injection control for driving the injector 16 based on the above-described sensor information, ignition timing control for igniting the mixture gas, pump control for driving the fuel pump 26, idle speed control for controlling the opening degree of the ISCV14 when the engine 1 is idling, idle abnormality detection control for detecting idle abnormality due to open-fixation of the ISCV14 or erroneous learning, and the like.

In the fuel injection control executed by the ECU31, the target fuel injection amount is determined based on the engine speed Ne calculated from the signal of the electromagnetic pickup 32, the throttle opening θ th detected by the throttle sensor 33, and the like. Then, the injector 16 is driven at a predetermined timing in the intake stroke to inject fuel.

Further, in the ignition timing control executed by the ECU31, the target ignition timing is determined based on the engine speed Ne, the throttle opening θ th, and the like. The ECU31 performs waveform shaping on the signal of the electromagnetic pickup 32 and generates a crank angle signal of a rectangular waveform synchronized with the variable reluctance rotor 7a (in other words, crank angle). Then, a target ignition timing is determined based on the crank angle signal.

In the pump control executed by the ECU31, the fuel pump 26 is driven and the fuel pressurized to a predetermined pressure is supplied to the injector 16 when the engine 1 is operated in a normal mode, which is one of the operating modes of the vehicle. On the other hand, when shifting to a fuel cut mode, which is one of the operating modes of the vehicle, during pump control, the fuel pump 26 is stopped from driving when a predetermined condition is satisfied, thereby stopping the supply of fuel to the injector 16.

The ECU31 functions as a fuel cut element and executes mode switching control between a normal mode and a fuel cut mode, which will be described below.

On the premise that the initial mode is the normal mode, the switching from the normal mode to the fuel cut mode can be performed only when all the following conditions (1) to (3) are satisfied.

(1) The elapsed time t1 after the engine 1 is started or the elapsed time t1 after the previous fuel cut mode is returned to the normal mode is equal to or longer than the predetermined time t1 s.

(2) The engine speed Ne is greater than a predetermined first upper limit speed Neu 1.

(3) The throttle opening θ th is smaller than a predetermined throttle lower limit opening θ thl.

The vehicle state is a state in which fuel cut is required, for example, when the vehicle is traveling on a downhill with inertia.

When the vehicle is operated in the fuel cut mode, the fuel cut mode is switched to the normal mode when any of the following conditions (1) and (2) is satisfied.

(1) The engine speed Ne is equal to or less than the second upper limit speed Neu 2.

(2) The throttle opening θ th is equal to or greater than a predetermined throttle lower limit opening θ thl.

Next, the next switching to the fuel cut mode is determined again as appropriate. The predetermined time t1s, the first upper limit rotation speed Neu1, the second upper limit rotation speed Neu2, and the throttle lower limit opening θ th1 are appropriately set to appropriate values. For example, the first upper limit rotation number Neu1 and the second upper limit rotation number Neu2 are set in advance such that "the first upper limit rotation number Neu1 > the second upper limit rotation number Neu 2" holds. However, without being limited to this, the same upper limit rotation number Neu may be set as the first upper limit rotation number Neu1 and the second upper limit rotation number Neu 2.

On the other hand, the ECU31 functions as a control element for updating the drive duty ratio of the ISCV14 as the idle speed control based on the engine speed Ne detected from the signal of the electromagnetic pickup 32 and the throttle opening θ th detected by the throttle sensor 33. Thus, even if the throttle opening θ th of the throttle valve 13 is maintained in the fully closed or slightly opened state when the engine 1 is idling by controlling the opening degree of the ISCV14, the engine speed Ne can be maintained at the preset target speed Net by adjusting the intake air amount to the engine 1 by controlling the opening degree of the ISCV 14.

However, when the dirt adhering to the ISCV14 becomes hard and the ISCV14 is opened and fixed, the ISCV14 cannot be controlled when the engine 1 is idling, and the amount of intake air to the engine 1 is increased, so that the engine speed Ne may increase to an unexpected speed, and in this case, the idling control of the engine 1 cannot be appropriately performed.

Further, as described above, since the correction value of the drive duty ratio of the ISCV14 is determined based on learning, the opening degree of the ISCV14 may not be appropriately controlled by erroneous learning due to the operating conditions of the vehicle or the like, and an idling abnormality of the engine 1 may occur.

Therefore, in the present embodiment, the ECU31 executes the above-described idle abnormality detection control to detect the idle abnormality of the engine 1, accurately identify the cause thereof, and reliably suppress the increase in the number Ne of engine revolutions at idle. The ECU31 functions as an abnormality determination element, and first, performs the determination of the provisional determination A, B, and based on the result, the provisional determination is made that the ISCV14 is open-fixed.

Next, the ECU31 functions as an abnormality specification element, and performs the determinations of the ISCV open/fixed determination X and the ISCV mis-learning determination Y only when any condition of the provisional determination A, B is satisfied. That is, in the idle abnormality detection control according to the present embodiment, by performing two stages of abnormality detection determination based on the two tentative determinations A, B and the two determination determinations X, Y, it is possible to identify and respond to the exact cause of the idle abnormality of the engine 1.

The following describes the procedure of the tentative determination a executed by the ECU31, with reference to the flowchart of fig. 2.

When the step of tentatively determining a starts, first, in step S11, it is determined whether or not the throttle opening θ th is equal to or less than a predetermined first opening threshold θ ths 1. When the determination result is yes, the process proceeds to step S12, whereas when the determination result is no, the process continues to the same determination at step S11.

In step S12, it is determined whether or not the neutral SW37 is on or the clutch SW38 is on, that is, whether or not the engine 1 is idling. If the determination result is yes, the process proceeds to step S13, whereas if the determination result is no, the process returns to step S11 to determine again.

In step S13, it is determined whether or not the fuel cut frequency Nfc, which is the number of times of shifting to the fuel cut mode, is equal to or greater than a predetermined frequency threshold Nfcs within a predetermined time. If the determination result is yes, the process proceeds to step S14, whereas if the determination result is no, the process returns to step S11 to determine again.

In step S14, it is determined that the condition for tentative determination a is satisfied, and the present step ends. The first opening degree threshold θ ths1 and the count threshold Nfcs are appropriately set to appropriate values.

As described above, in the tentative determination a, only when the determination results of steps S11 to S13 are all yes, the tentative determination is that the ISCV14 is open-fixed. The condition of the determination a is temporarily satisfied when the vehicle is in the following state: the engine 1 idles, and the engine speed Ne continues to increase and fuel cut frequently even though the throttle opening θ th is in a reduced state, and a state where the ISCV14 is opened and fixed is suspected.

Hereinafter, the procedure of the tentative determination B executed by the ECU31 will be described with reference to the flowchart of fig. 3.

When the step of tentatively determining B is started, first, in step S21, it is determined whether or not the engine speed Ne is greater than a predetermined first speed threshold Nes 1. When the determination result is yes, the process proceeds to step S22, whereas when the determination result is no, the process continues to the same determination at step S21.

In step S22, it is determined whether or not engine revolution number Ne is equal to or greater than a value obtained by adding target revolution number Net preset in ECU31 and predetermined second revolution number threshold Nes 2. If the determination result is yes, the process proceeds to step S23, whereas if the determination result is no, the process returns to step S21 to determine again.

In step S23, it is determined whether a crank angle signal is input, in other words, whether a signal of the electromagnetic pickup 32 is detected. If the determination result is yes, the process proceeds to step S24, whereas if the determination result is no, the process stands by at step S23 until a crank signal is input.

In step S24, it is determined whether or not the throttle opening θ th is equal to or less than a predetermined second opening threshold θ th 2. That is, it is determined whether or not the throttle opening θ th is not once larger than the second opening threshold θ th2, in other words, whether or not the vehicle is in a stopped state after the crank angle signal is input. If the determination result is yes, the process proceeds to step S25, whereas if the determination result is no, the process returns to step S21 to determine again.

In step S25, it is determined whether or not the neutral SW37 is on, or the clutch SW38 is on, that is, whether or not the engine 1 is idling. If the determination result is "yes", the process proceeds to step S26, and if the determination result is "no", the process returns to step S21 to perform the determination again.

In step S26, it is determined whether or not engine speed Ne is less than a predetermined third speed threshold Nes3 after ECU31 is started, that is, after the key is turned on. If the determination result is "yes", the process proceeds to step S27, and if the determination result is "no", the process returns to step S21 to perform the determination again.

In step S27, it is determined whether or not the elapsed time t2 after the start of ECU31, that is, after key-on, is within a predetermined time t2S and the determination result in step S26 becomes yes. When the determination result is yes, the process proceeds to step S28. On the other hand, when the determination result is "no", it returns to step S21 to determine again.

In step S28, it is determined whether or not the duration t3 during which yes is established in all the determination results in steps S21 to S27 is equal to or longer than a predetermined time t 3S. When the determination result is yes, the process proceeds to step S29. On the other hand, if the determination result is "no", the process proceeds to step S21, and it is determined whether or not the "yes" of all the determination results of steps S21 to S27 is satisfied and maintained for the predetermined time t3S or more.

In step S29, it is determined that the condition for tentative determination B is satisfied, and the present step ends. The first rotation number threshold Nes1, the target rotation number Net, the second rotation number threshold Nes2, the second opening degree threshold θ ths2, the third rotation number threshold Nes3, the predetermined time t2s, and the predetermined time t3s are appropriately set to appropriate values. For example, the first revolution number threshold Nes1, the second revolution number threshold Nes2, and the third revolution number threshold Nes3 are set in advance such that "the second revolution number threshold Nes2 > the first revolution number threshold Nes1 > the third revolution number threshold Nes 3" holds. For example, the first opening degree threshold θ ths1 and the second opening degree threshold θ ths2 are set in advance such that "the first opening degree threshold θ ths1 is satisfied as the second opening degree threshold θ ths 2".

As described above, in the tentative determination B, only when the determination results of steps S21 to S28 are all yes, the tentative determination is that the ISCV14 is open-fixed. The condition for temporarily determining B is satisfied when the vehicle is in the following state: the engine 1 is idling, and a state in which the ISCV14 is open and fixed is suspected, such as the engine speed Ne continues to rise even though the throttle opening θ th is in a reduced state and the fuel cut is not performed.

Hereinafter, the procedure of determining the determination X executed by the ECU31 will be described with reference to the flowchart of fig. 4.

Before the step of determining the determination X is started, first, as a precondition determination, it is determined whether or not at least one of the conditions of the above-described provisional determination A, B is satisfied in step S31. When the determination result is yes, the process proceeds to step S32, whereas when the determination result is no, the process continues to the same determination at step S31.

In step S32, the drive duty of the ISCV14 is forcibly set to zero, and the process proceeds to step S33.

In step S33, it is determined whether or not engine revolution Ne is greater than a value obtained by adding target revolution Net preset in ECU31 and predetermined fourth revolution threshold Nes 4. If the determination result is yes, the process proceeds to step S34, whereas if the determination result is no, the process returns to step S31 to determine again.

In step S34, it is determined whether the drive duty ratio of the ISCV14 is zero. If the determination result is yes, the process proceeds to step S35, whereas if the determination result is no, the process returns to step S33 to determine again.

In step S35, it is determined whether or not the throttle opening θ th is equal to or less than a predetermined third opening threshold θ th 3. If the determination result is yes, the process proceeds to step S36, whereas if the determination result is no, the process returns to step S33 to determine again.

In step S36, it is determined whether or not the duration t4 during which yes is established in all the determination results in steps S33 to S35 is equal to or longer than a predetermined time t 4S. When the determination result is yes, the process proceeds to step S37. On the other hand, if the determination result is "no", the process proceeds to step S33, and it is determined in step S36 whether or not all of the determinations in steps S33 to S35 are true for the predetermined time t4S or longer.

In step S37, the determination is made that the condition for determining X is satisfied, and the process proceeds to step S38.

In step S38, the vehicle shifts to the fuel cut mode, and the present step ends. The target rotation number Net, the fourth rotation number threshold Nes4, the third opening degree threshold θ ths3, and the predetermined time t4s are appropriately set to appropriate values. For example, the fourth threshold ns 4 is preset so that "the second threshold ns 2 is satisfied when the second threshold ns 2 is satisfied. For example, the third opening degree threshold θ ths3 is preset such that "the third opening degree threshold θ ths3 is satisfied as the second opening degree threshold θ ths 2".

As described above, in the determination X, only when all the determination results of steps S33 to S36 are yes, it is determined that the ISCV14 is open-fixed, and thereafter, the increase in the engine speed Ne due to the open-fixed of the ISCV14 is reliably suppressed by performing the fuel cut.

Determining that the condition of determination X is satisfied when the vehicle is in the following state, on the basis of the condition of provisional determination a or B: after the drive duty ratio of the ISCV14 is forcibly set to zero, the state in which the ISCV14 is fixed to be open can be determined by, for example, continuing to increase the engine speed Ne even if the drive duty ratio is kept at zero.

The following describes the procedure of determining the determination Y by the ECU31, with reference to the flowchart of fig. 5.

Before the step of determining the determination Y is started, as in the case of determining the determination X, first, as a precondition determination, it is determined whether or not at least one of the tentative determinations A, B is established in step S41. When the determination result is yes, the process proceeds to step S42, whereas when the determination result is no, the process continues to the same determination at step S41.

In step S42, the drive duty of the ISCV14 is forcibly set to zero, and the process proceeds to step S43.

In step S43, it is determined whether or not engine revolution number Ne is equal to or less than a value obtained by adding target revolution number Net preset in ECU31 and predetermined fifth revolution number threshold Nes 5. If the determination result is yes, the process proceeds to step S44, whereas if the determination result is no, the process returns to step S43 to determine again.

In step S44, it is determined whether or not the duration t5 during which yes is satisfied as a result of the determination in step S43 is equal to or longer than a predetermined time t 5S. When the determination result is yes, the process proceeds to step S45. On the other hand, if the determination result is "no", the process proceeds to step S43, and it is determined whether or not "yes" of the determination result of step S43 is satisfied and maintained for the predetermined time t5S or more.

In step S45, the determination is made that the condition for determining Y is satisfied, and the process proceeds to step S46.

In step S46, the correction value is updated so that the drive duty ratio of the ISC14 is decreased, and the present step ends. In addition, target rotation number Net, fifth rotation number threshold Nes5, and predetermined time t5s are appropriately set to appropriate values. For example, the fifth rotation number threshold Nes5 is preset such that "the fifth rotation number threshold Nes5 is satisfied when the fourth rotation number threshold Nes4 is satisfied.

As described above, in the determination Y, it is determined that the error learning of the ISCV14 is generated only when the determination results of steps S43, S44 are all yes, and thereafter the increase in the engine revolution number Ne due to the error learning of the ISCV14 is reliably suppressed by updating the correction value to decrease the drive duty ratio of the ISCV 14.

Determining that the condition for determining Y is satisfied when the vehicle is in the following state, on the basis of the condition for tentatively determining a or B: after the drive duty ratio of the ISCV14 is forcibly set to zero, the drive duty ratio is increased by the correction value based on the error learning of the ISCV14, and the engine speed Ne is slightly increased, but the state of the error learning of the ISCV14 can be determined without a state of continuing the increase or the like.

As described above, in the present embodiment, when the condition for the provisional determination a is satisfied, the following vehicle state can be detected: the engine 1 is idling, and the engine speed Ne continues to rise and the fuel cut is frequent even though the throttle opening θ th is in a reduced state, and it is suspected that the ISCV14 is open and fixed.

On the other hand, when the condition for provisional determination B is satisfied, the following vehicle state can be detected: the engine 1 is idling, and it is suspected that the ISCV14 is open and fixed, for example, the engine speed Ne continues to rise even though the fuel cut is not performed even though the vehicle is stopped and the throttle opening θ th is reduced.

Further, when the condition for determining the judgment X is satisfied, the following vehicle state can be detected: after the drive duty ratio of the ISCV14 is forcibly set to zero after the condition of the provisional determination a or B is made, the engine speed Ne continues to increase even if the drive duty ratio remains zero, and the open-fixed state of the ISCV14 can be determined.

On the other hand, when the condition for determining Y is satisfied, the following vehicle state can be detected: after the drive duty ratio of the ISCV14 is forcibly set to zero after the condition of a or B is tentatively determined, the drive duty ratio is increased by the correction value based on the erroneous learning of the ISCV14 to slightly increase the engine speed Ne, but it is not in a state of continuing the increase, and therefore it is determined that the erroneous learning of the ISCV14 is not the open fixation of the ISCV 14.

By performing the tentative determination A, B and the determination X, Y, it is possible to detect the idling abnormality of the engine 1 and accurately determine whether the cause thereof is the open-fixation of the ISCV14 or the erroneous learning of the ISCV 14. Further, when the ISCV14 is open-fixed, fuel cut is performed, and on the other hand, when the ISCV14 is erroneously learned, the correction value is updated to reduce the drive duty ratio of the ISCV14, whereby an unexpected increase in the engine speed Ne at idling can be reliably suppressed.

While the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various changes can be made without departing from the scope of the invention.

For example, in the idle abnormality detection control according to the above embodiment, both the provisional determination A, B are determined, and then, when at least one of the conditions of the provisional determination A, B is satisfied, both the determination X, Y are determined. In the above-described idle abnormality detection control, by performing the abnormality detection determination in two stages based on the two tentative determinations A, B and the two determination determinations X, Y, it is possible to identify and respond to the exact cause of the idle abnormality of the engine 1.

However, the present invention is not limited to this, and both or only one of the determination determinations X, Y may be performed after only one of the provisional determinations A, B is performed. Further, the determination of the open-fixed state of the ISCV14 may be determined based on only the result of the satisfaction of both or one of the tentative determinations A, B without performing the determination X, Y. Even in the above case, the cause of the idling abnormality of the engine 1 can be identified and dealt with a predetermined accuracy.

(symbol description)

1 Engine

11 air intake passage

13 throttle valve

14 ISCV (Idle speed control valve)

15 bypass passage

31 ECU (Fuel cut element, control element, abnormality judgment element, abnormality determination element)

32 electromagnetic pickup (revolution sensor)

33 throttle sensor

Claims

1. A control device for a vehicle engine, characterized by comprising:

an intake passage connected to the engine;

a throttle valve provided in the intake passage;

a bypass passage that is connected to the intake passage and that bypasses the throttle valve;

an idle speed control valve provided in the bypass passage;

a revolution sensor that detects the number of engine revolutions;

a throttle sensor that detects a throttle opening of the throttle valve;

a fuel cut-off element that cuts off fuel supply to the engine when the engine speed is greater than a prescribed upper limit speed and the opening is less than a prescribed lower limit opening while the engine is idling;

a control element that controls an opening degree of the idle speed control valve based on the engine revolution detected by the revolution sensor and the throttle opening degree detected by the throttle sensor so as to maintain the engine revolution at a preset target revolution when the engine is idling; and

an abnormality determination unit that determines that an idling abnormality has occurred when the throttle opening is equal to or less than a predetermined first opening threshold and the number of times of fuel cut by the fuel cut unit is equal to or more than a predetermined number threshold within a predetermined time while the engine is idling,

the control means determines a correction value for correcting the opening degree of the idle speed control valve when the engine is idling by learning, and sets the drive duty of the idle speed control valve to zero after it is determined by the abnormality determination means that the idle speed abnormality has occurred,

the control device for the vehicle engine further includes an abnormality determining element that determines that the erroneous learning of the correction value learned by the control element has occurred as the idling abnormality when a state in which the engine revolution is equal to or less than a value obtained by adding the target revolution to a predetermined fifth revolution threshold continues for a predetermined time.

2. A control device for a vehicle engine, characterized by comprising:

an intake passage connected to the engine;

a throttle valve provided in the intake passage;

an idle speed control valve provided in the bypass passage;

a revolution sensor that detects the number of engine revolutions;

a throttle sensor that detects a throttle opening of the throttle valve;

a control element that adjusts an opening degree of the idle speed control valve based on the engine revolution detected by the revolution sensor and the throttle opening degree detected by the throttle sensor, and maintains the engine revolution at a preset target revolution when the engine is idling; and

an abnormality determination unit that determines that an idling abnormality has occurred when the engine speed is greater than a predetermined first speed threshold value, the engine speed is greater than or equal to a value obtained by adding the target speed to a predetermined second speed threshold value that is greater than the first speed threshold value, and the engine speed is less than a predetermined third speed threshold value that is less than the first speed threshold value within a predetermined time after a key is turned on from a stopped state to activate the control unit, and a state in which determination results regarding all of the first speed threshold value, the second speed threshold value, and the third speed threshold value have been previously satisfied continues for a predetermined time,

3. A control device for a vehicle engine, characterized by comprising:

an intake passage connected to the engine;

a throttle valve provided in the intake passage;

an idle speed control valve provided in the bypass passage;

a revolution sensor that detects the number of engine revolutions;

a throttle sensor that detects a throttle opening of the throttle valve;

the control means sets the drive duty of the idle speed control valve to zero after the abnormality determination means determines that the idle speed abnormality has occurred,

the control device for the vehicle engine further includes an abnormality determination unit that determines that the idle speed control valve is in an open state fixed and open fixed when the idle speed control valve is in an open state as the idle abnormality when the engine speed is greater than a value obtained by adding the target speed to a predetermined fourth speed threshold and the drive duty is zero for a predetermined time,

the control element determines a correction value that corrects the opening degree of the idle speed control valve when the engine is idling by learning,

when the state where the engine revolution number is equal to or less than a value obtained by adding the target revolution number and a predetermined fifth revolution number threshold value continues for a predetermined time, the abnormality determination element determines that the erroneous learning of the correction value learned by the control element has occurred as the idling abnormality.

4. A control device for a vehicle engine, characterized by comprising:

an intake passage connected to the engine;

a throttle valve provided in the intake passage;

an idle speed control valve provided in the bypass passage;

a revolution sensor that detects the number of engine revolutions;

a throttle sensor that detects a throttle opening of the throttle valve;

the fuel cut-off element cuts off the supply of fuel to the engine when it is determined by the abnormality determining element that the open fixation of the idle speed control valve is generated,

5. A control device for a vehicle engine, characterized by comprising:

an intake passage connected to the engine;

a throttle valve provided in the intake passage;

an idle speed control valve provided in the bypass passage;

a revolution sensor that detects the number of engine revolutions;

a throttle sensor that detects a throttle opening of the throttle valve;

6. The control device of an engine for a vehicle according to any one of claims 1 to 5,

when it is determined by the abnormality determining element that the erroneous learning of the correction value has occurred, the control element changes the correction value so that the drive duty of the idle speed control valve is decreased.